Dynamo-electric machine



SePt- 8, 1936. J. F. CALVERT 2,053,422

DYNAMO-ELECTRIC MACHINE Filedv Feb. 7, 1934 WITNESSES INVENTOR Patented Sept. 8, '1936 PATENT oFElcE DYNAMO -ELECTRIC MACHINE J ohn F. Calvert, Irwin, Pa., assigner to Westinghouse Electric &,Manu.faoturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 7, 1934, Serial No. 719,103

4 Claims. (Cl. 17h-206) The invention relates generally to dynamoelectric machines and more particularly to the protection oi the windings of dynamo-electric machines from electro-static discharges and the heating of the insulation.

The object of the invention is to provide for conducting to the armature iron or other ground the electro-static charges accumulated on the insulated conductors of the different coils oi the armature windings of a dynamowelectric reef chine, to restrict the electro-static discharge be tween the diierent conductors and' the heating oi the insulation.

Other objectswill in part be obvious and part appear hereinater.

The invention accordingly is disclosed 'in accompanying drawing and comprises the iene tures or" construction, combination or" element and arrangement of parts which will ne emplied in the structure hereinafter et forth and the scope oi the application of which will be indicated in the claims.

lor a fuller understanding of the nature and objects oi the invention, reference may be to the following detailed description taiien in conjunction with the accompanying drawing which:

Figure l is a view in section oi the end loops of a winding of a dynamo-electric machine constructed in accordance with this invention.

Fig. 2 is a diagrammatic view oi athree-phase Winding of a dynamo-electric machine illustrating the application of the present invention.

Fig. 3 is a view in section showing the manner in which the present invention may be applied to a connection between a dynamo-electric machine and a conductor ior distributing power; and,

Fig. 4 is a view in section illustrating how a dynamo-electric machine constructed in accordance with this invention may be connected to a bushing for dissipating accumulated electro- Referring now to the drawing and Figs. l to 3 in particular, it will be observed that the different phase windings or armature coils I0 of a multiple phase dynamo-electric machine are disposed in close proximity to one another. The windings l0 are of the usual type and are pro- ;vided with heavy layers of insulating material best illustrated at il.

In operation, electro-static charges are accumulated on the surfaces of these insulated windings. The potential of certain coils is equal to the terminal to ground rvoltage of the machine. When machines are designed to generate high voltages, these electro-static charges may cause discharges between the different phase windings which may cause a considerable erosion of the insulation. Even if such discharges do not seriously damage the insulation, they are objectionable because oi the possible iire hazard and the generation of acids which are damaging lto the insulation.

In order to restrict the electro-static discharges between the different nhase'windings oi dynanioelectric machines, come suitable conducting me.- 'terial l2 is applied to the surface oi the Windings. e. number of suitable materials are availw able on the market. Good results have been ob tained by utilising conducting material known es aauadag whi a is e, graphite suspended we reatoA el essentially a mixture or" graphite and we er paint. 'When the windings are thus coated l n a conducting material such as aquaiiag, the accumuiatedele-ctro-static charges are conducted inwardly along the end loop por-s tions of the windings to armattue iron 'in this manner the eiectroesta-tic charges eccumuleted may be dissipated by conducting them oh to the armature iron which is at ground 32o tential.

ln the showings in 2, conn denser bushings -lfl are provided so that the ground sheath o aquadag or other conducting material on the end loop portions and connecw tions may be terminated here without damage to the insulation of the end loop portions and connections. As shown in Fig. Ll, the aquadag i2 is applied to the windings of the dynamo-electric machine and to the conductors leading to the bushings lli.

This method of connecting to the condenser bushings to dissipate the accumulation oi the electro-static charges is now possible, since satisfactory joints may be made between the different conductors. This is made possible by the improvements in insulating material which enables the owing together of the insulating materials provided on the different conductors with the result that the insulation becomes substantially mechanically homogeneous throughout and will resist substantially as high potential at that point as elsewhere in the windings or conductor I 6 \1eading fromv the joint. f

In the construction such as shown in Fig. 3, when the leads are broughtout from the armature to V'a metal sheathed cable shown generally at I1, the aquadag I2 is extended to contact with the metal sheathing I8 which in most instances will be lead In this manner the accumulated electro-static charges are conducted to the sheathing I8 and may then be dissipated in a manner that is best adapted to the operating conditions.

The bushings I4 employed for terminating the Y conducting sheathing are of well known construction comprising layers of insulating material such as shown at I9 in Fig. 4 and layers of tinioil 20 superimposed on the insulating layers I 9, and a bush 2l. This type of structure has been found very satisfactory for dissipating electrostatic charges.

In conclusion, it is pointed out that while the illustrated example constitutes a practical embodiment of the invention, I do not limit myself to the exact details shown since modications of the same may be considerably varied without departing from the spirit of the invention as deiined in the appended claims.

I claim as my invention:

1. In a dynamo-electric machine, in combination, armature iron provided with slots, insulated multiple phase windings disposed in the armature slots and extending beyond the armature iron presenting end loop portions, a conducting material applied to the surface only of the insulation, the conducting material extending outwardly from the iron to cover completely the end turn portions to dissipate energy 'and prevent a discharge between the coils of the different phase windings, and means connected with lthe conducting material for dissipating energy; l

2. In a. dynamo-electric machine, in combination, armature iron lated multiple phase windings disposed in the provided with slots, insuing beyond the armature iron presenting end turn portions, and a conducting material applied to i'qhfmurfacefo'nly of the armature coils and out,- wardly beyond the armature iron to the terminals of the machine to carry electrostatic charges and protect the coils from corona discharge between thevturns of different phases and the heating of the insulation.

4. In a dynamo-electric machine, in combination, armature iron provided with slots, insulated multiple phase windings disposed in the armature slots and extending beyond the armature iron presenting end looped portions, a conducting material applied to the surface only of the windings to make electrical contact with the armature iron, the conducting material extending outwardly from the iron covering entirely the windings to the terminals of the machine to dissipate electrostatic charges and prevent a discharge be`- tween the turns of the diierent phase windings, and means connected with the conducting material applied to the windings for dissipating energy.

J OHN F. CALVERT. 

